Heterocyclic aspartyl protease inhibitors

ABSTRACT

Disclosed are compounds of the formula I 
                         
or a stereoisomer, tautomer, or pharmaceutically acceptable salt or solvate thereof, wherein Ar, R 1 , R 2 , R 3 , R 4  and R 5  are as defined in the specification; and pharmaceutical compositions comprising the compounds of formula I.
 
     Also disclosed is the method of inhibiting aspartyl protease, and in particular, the methods of treating cardiovascular diseases, cognitive and neurodegenerative diseases. Also disclosed are methods of treating cognitive or neurodegenerative diseases using the compounds of formula I in combination with a cholinesterase inhibitor or a muscarinic m 1  agonist or m 2  antagonist.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of application U.S. Ser. No. 12/794,858, filed Jun. 7, 2010, which is a Divisional of U.S. Ser. No. 11/586,151, filed Oct. 25, 2006, now U.S. Pat. No. 7,763,606, which claims the benefit of U.S. Provisional Application No. 60/730,622 filed Oct. 27, 2005, each of which is incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to aspartyl protease inhibitors, pharmaceutical compositions comprising said compounds, their use in the treatment of cardiovascular diseases, cognitive and neurodegenerative diseases, and their use as inhibitors of the Human Immunodeficiency Virus, plasmepsins, cathepsin D and protozoal enzymes.

BACKGROUND

Human aspartic proteases of the A1 (pepsin-like) family are as follows: pepsin A and C, renin, BACE-1, BACE 2, Napsin A, cathepsin D in pathological conditions.

The role of renin-angiotensin system (RAS) in regulation of blood pressure and fluid electrolyte has been well established (Oparil, S, etal. N Engl J Med 1974; 291:381-401/446-57). The octapeptide Angiotensin-II, a potent vasoconstrictor and stimulator for release of adrenal aldosterone, was processed from the precursor decapeptide Angiotensin-I, which in turn is processed from angiotensinogen by the renin enzyme. Angiotensin-II is also found to play roles in vascular smooth muscle cell growth, inflammation, reactive oxygen species generation and thrombosis and influence atherogenesis and vascular damage. Clinically, the benefit of interruption of the generation of angiotensin-II through antagonism of conversion of angiotensin-I has been well known and there are a number of ACE inhibitor drugs on the market. The blockade of the earlier conversion of angiotensinogen to angiotensin-I, i.e. the inhibition of renin enzyme, is expected to have similar but not identical effects. Since renin is an aspartyl protease whose only natural substrate is angiotensinogen, it is believed that there would be less frequent adverse effect for controlling high blood pressure and related symptoms regulated by angiotensin-II through its inhibition.

Another protease, Cathepsin-D, is involved in lysosomal biogenesis and protein targeting, and may also be involved in antigen processing and presentation of peptide fragments. It has been linked to numerous diseases including, Alzheimer's, Disease, connective tissue disease, muscular dystrophy and breast cancer.

Alzheimer's Disease (AD) is a progressive neurodegenerative disease that is ultimately fatal. Disease progression is associated with gradual loss of cognitive function related to memory, reasoning, orientation and judgment. Behavioral changes including confusion, depression and aggression also manifest as the disease progresses. The cognitive and behavioral dysfunction is believed to result from altered neuronal function and neuronal loss in the hippocampus and cerebral cortex. The currently available AD treatments are palliative, and while they ameliorate the cognitive and behavioral disorders, they do not prevent disease progression. Therefore there is an unmet medical need for AD treatments that halt disease progression.

Pathological hallmarks of AD are the deposition of extracellular β-amyloid (Aβ) plaques and intracellular neurofibrillary tangles comprised of abnormally phosphorylated protein tau. Individuals with AD exhibit characteristic Aβ deposits, in brain regions known to be important for memory and cognition. It is believed that Aβ is the fundamental causative agent of neuronal cell loss and dysfunction which is associated with cognitive and behavioral decline. Amyloid plaques consist predominantly of Aβ peptides comprised of 40-42 amino acid residues, which are derived from processing of amyloid precursor protein (APP). APP is processed by multiple distinct protease activities. Aβ peptides result from the cleavage of APP by β-secretase at the position corresponding to the N-terminus of Aβ, and at the C-terminus by γ-secretase activity. APP is also cleaved by α-secretase activity resulting in the secreted, non-amyloidogenic fragment known as soluble APP.

An aspartyl protease known as BACE-1 has been identified as the β-secretase activity responsible for cleavage of APP at the position corresponding to the N-terminus of Aβ peptides.

Accumulated biochemical and genetic evidence supports a central role of Aβ in the etiology of AD. For example, Aβ has been shown to be toxic to neuronal cells in vitro and when injected into rodent brains. Furthermore inherited forms of early-onset

AD are known in which well-defined mutations of APP or the presenilins are present. These mutations enhance the production of Aβ and are considered causative of AD. Since Aβ peptides are formed as a result of β-secretase activity, inhibition of BACE-1 should inhibit formation of Aβ peptides. Thus inhibition of BACE-1 is a therapeutic approach to the treatment of AD and other cognitive and neurodegenerative diseases caused by Aβ deposition.

Human immunodeficiency virus (HIV), is the causative agent of acquired immune deficiency syndrome (AIDS). It has been clinically demonstrated that compounds such as indinavir, ritonavir and saquinavir which are inhibitors of the HIV aspartyl protease result in lowering of viral load. As such, the compounds described herein would be expected to be useful for the treatment of AIDS. Traditionally, a major target for researchers has been HIV-1 protease, an aspartyl protease related to renin.

In addition, Human T-cell leukemia virus type I (HTLV-I) is a human retrovirus that has been clinically associated with adult T-cell leukemia and other chronic diseases. Like other retroviruses, HTLV-I requires an aspartyl protease to process viral precursor proteins, which produce mature virions. This makes the protease an attractive target for inhibitor design. (Moore, et al. Purification of HTLV-I Protease and Synthesis of Inhibitors for the treatment of HTLV-I Infection 55^(th) Southeast Regional Meeting of the American Chemical Society, Atlanta, Ga., US Nov. 16-19, 2003 (2003), 1073. CODEN; 69EUCH Conference, AN 2004:137641 CAPLUS).

Plasmepsins are essential aspartyl protease enzymes of the malarial parasite.

Compounds for the inhibition of aspartyl proteases plasmepsins, particularly I, II, IV and HAP, are in development for the treatment of malaria. (Freire, et al. WO 2002074719. Na Byoung-Kuk, et al., Aspartic proteases of Plasmodium vivax are highly conserved in wild isolates, Korean Journal of Parasitology (2004 June), 42(2) 61-6. Journal code: 9435800) Furthermore, compounds used to target aspartyl proteases plasmepsins (e.g. I, II, IV and HAP), have been used to kill malarial parasites, thus treating patients thus afflicted.

Compounds that act as aspartyl protease inhibitors are described, for example, in U.S. Ser. No. 11/010,772, filed on Dec. 13, 2004, herein incorporated by reference.

SUMMARY OF THE INVENTION

The present invention relates to compounds having the structural formula I

or a stereoisomer, tautomer, pharmaceutically acceptable salt or solvate thereof, wherein

W is —S(O)—, —S(O)₂—, —C(═O)—, —O—, —C(═S)—, —C(R⁶)(R⁷)—, —N(R⁵)—, —P(O)(OR¹⁵)— or —C(═N(R⁵))—;

Ar is arylene or heteroarylene, wherein Ar is independently unsubstituted or substituted by 1 to 5 R¹⁴ groups;

R¹, R² and R⁵ are independently selected from the group consisting of H, alkyl, arylalkyl, heteroarylalkyl, cycloalkylalkyl, heterocycloalkylalkyl, arylcycloalkylalkyl, heteroarylcycloalkylalkyl, arylheterocycloalkylalkyl, heteroarylheterocycloalkylalkyl, cycloalkyl, arylcycloalkyl, heteroarylcycloalkyl, heterocycloalkyl, arylheterocycloalkyl, heteroarylheterocycloalkyl, alkenyl, arylalkenyl, cycloalkenyl, arylcycloalkenyl, heteroarylcycloalkenyl, heterocycloalkenyl, arylheterocycloalkenyl, heteroaryiheterocycloalkenyl, alkynyl, arylalkynyl, aryl, cycloalkylaryl, heterocycloalkylaryl, heterocycloalkenylaryl, heteroaryl, cycloalkylheteroaryl, heterocycloalkylheteroaryl, cycloalkenylaryl, heterocycloalkenylaryl, —OR¹⁵, —CN, —C(O)R⁸, —C(O)OR⁹, —S(O)R¹⁰, —S(O)₂R¹⁰, —C(O)N(R¹¹)(R¹²), —S(O)N(R¹¹)(R¹²), —S(O)₂N(R¹¹)(R¹²), —NO₂, —N═C(R⁸)₂ and —N(R⁸)₂;

R³, R⁴, R⁶ and R⁷ are independently selected from the group consisting of H, alkyl, arylalkyl, heteroarylalkyl, cycloalkylalkyl, heterocycloalkylalkyl, arylcycloalkylalkyl, heteroarylcycloalkylalkyl, arylheterocycloalkylalkyl, heteroarylheterocycloalkylalkyl, cycloalkyl, arylcycloalkyl, heteroarylcycloalkyl, heterocycloalkyl, arylheterocycloalkyl, heteroarylheterocycloalkyl, alkenyl, arylalkenyl, cycloalkenyl, arylcycloalkenyl, heteroarylcycloalkenyl, heterocycloalkenyl, arylheterocycloalkenyl, heteroarylheterocycloalkenyl, alkynyl, arylalkynyl, aryl, cycloalkylaryl, heterocycloalkylaryl, heterocycloalkenylaryl, heteroaryl, cycloalkylheteroaryl, heterocycloalkylheteroaryl, cycloalkenylaryl, heterocycloalkenylaryl, —CH₂—O—Si(R⁹)(R¹⁰)(R¹⁹), —CN, —C(O)R⁸, —C(O)OR⁹ or —C(O)N(R¹¹)(R¹²);

or optionally, R³, R⁴, R⁶ and R⁷, together with the carbon atom to which they are attached form a 3- to 8-membered cycloalkyl ring optionally substituted by 1 to 4 R¹⁴ moieties; wherein 1-5 of the atoms in the ring can be replaced by —O—; —S—; —N(R⁵)—; —C(O)—; —S(O)— or —S(O)₂—;

R⁸ is independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, —OR¹⁵, —N(R¹⁵)(R¹⁶), —N(R¹⁵)C(O)R¹⁶, —N(R¹⁵)S(O)R¹⁶, —N(R¹⁵)S(O)₂R¹⁶, —N(R¹⁵)S(O)₂N(R¹⁶)(R¹⁷), —N(R¹⁵)S(O)N(R¹⁶)(R¹⁷), —N(R¹⁵)C(O)N(R¹⁶)(R¹⁷) and —N(R¹⁵)C(O)OR¹⁶;

R⁹ is independently selected from the group consisting of H, alkyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl and heteroarylalkyl;

R¹⁰ is independently selected from the group consisting of H, alkyl, alkenyl, cycloalkyl, cycloalkylalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl and —N(R¹⁵)(R¹⁶);

R¹¹ and R¹² are independently selected from the group consisting of H, alkyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, —C(O)R⁸, —C(O)OR⁹, —S(O)R¹⁰, —S(O)₂R¹⁰, —C(O)N(R¹⁵)(R¹⁶), —S(O)N(R¹⁵)(R¹⁶) and —S(O)₂N(R¹⁵)(R¹⁶);

R¹⁴ is 1-5 substituents independently selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, halo, —CN, —OR¹⁵, —C(O)R¹⁵, —C(O)OR¹⁵, —C(O)N(R¹⁵)(R¹⁶), —SR¹⁵, —S(O)N(R¹⁵)(R¹⁶) —S(O)₂N(R¹⁵)(R¹⁶), —C(═NOR¹⁵)R¹⁶, —P(O)(OR¹⁵)(OR¹⁶), —N(R¹⁵)(R¹⁶), —N(R¹⁵)C(O)R¹⁶, —N(R¹⁵)S(O)R¹⁶, —N(R¹⁵)S(O)₂R¹⁶, —N(R¹⁵)S(O)₂N(R¹⁶)(R¹⁷), —N(R¹⁵)S(O)N(R¹⁶)(R¹⁷), —N(R¹⁵)C(O)N(R¹⁶)(R¹⁷) and —N(R¹⁵)C(O)OR¹⁶; R¹⁵, R¹⁶ and R¹⁷ are independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, arylcycloalkyl, aryiheterocycloalkyl, R¹⁸-alkyl, R¹⁸-cycloalkyl, R¹⁸-cycloalkylalkyl, R¹⁸-heterocycloalkyl, R¹⁸-heterocycloalkylalkyl, R¹⁸-aryl, R¹⁶-arylalkyl, R¹⁸-heteroaryl and R¹⁸-heteroarylalkyl; or

R¹⁵, R¹⁶ and R¹⁷ are

wherein R²³ numbers 0 to 5 substituents, m is 0 to 6 and n is 1 to 5;

R¹⁸ is 1-5 substituents independently selected from the group consisting of alkyl, alkenyl, aryl, arylalkyl, arylalkenyl, arylalkynyl, —NO₂, halo, heteroaryl, HO-alkyoxyalkyl, —CF₃, —CN, alkyl-CN, —C(O)R¹⁹, —C(O)OH, —C(O)OR¹⁹, —C(O)NHR²⁰, —C(O)NH₂, —C(O)N(alkyl)₂, —C(O)N(alkyl)(aryl), —C(O)N(alkyl)(heteroaryl), —SR¹⁹, —S(O)₂R²⁰, —S(O)NH₂, —S(O)NH(alkyl), —S(O)N(alkyl)(alkyl), —S(O)NH(aryl), —S(O)₂NH₂, —S(O)₂NHR¹⁹, —S(O)₂NH(heterocycloalkyl), —S(O)₂N(alkyl)₂, —S(O)₂N(alkyl)(aryl), —OCF₃, —OH, —OR²⁰, —O-heterocycloalkyl, —O-cycloalkylalkyl, —O-heterocycloalkylalkyl, —NH₂, —NHR²⁰, —N(alkyl)₂, —N(arylalkyl)₂, —N(arylalkyl)-(heteroarylalkyl), —NHC(O)R²⁰, —NHC(O)NH₂, —NHC(O)NH(alkyl), —NHC(O)N(alkyl)(alkyl), —N(alkyl)C(O)NH(alkyl), —N(alkyl)C(O)N(alkyl)(alkyl), —NHS(O)₂R²⁰, —NHS(O)₂NH(alkyl), —NHS(O)₂N(alkyl)(alkyl), —N(alkyl)S(O)₂NH(alkyl) and —N(alkyl)S(O)₂N(alkyl)(alkyl);

or two R¹⁸ moieties on adjacent carbons can be linked together to form

R¹⁹ is alkyl, cycloalkyl, aryl, arylalkyl or heteroarylalkyl;

R²⁰ is alkyl, cycloalkyl, aryl, halo substituted aryl, arylalkyl, heteroaryl or heteroarylalkyl;

and wherein each of the alkyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, alkenyl and alkynyl groups in R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², and R¹⁴ are independently unsubstituted or substituted by 1 to 5 R²¹ groups independently selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, halo, —CN, —OR¹⁵, —C(O)R¹⁵, —C(O)OR¹⁵, —C(O)N(R¹⁵)(R¹⁶), —SR¹⁵, —S(O)N(R¹⁵)(R¹⁶), —CH(R¹⁵)(R¹⁶), —S(O)₂N(R¹⁵)(R¹⁶), —C(═NOR¹⁵)R¹⁶, —P(O)(OR¹⁵)(OR¹⁶), —N(R¹⁵)(R¹⁶), -alkyl-N(R¹⁵)(R¹⁶), —N(R¹⁵)C(O)R¹⁶, —CH₂—N(R¹⁵)C(O)R¹⁶, —CH₂—R¹⁵; —N(R¹⁵)S(O)R¹⁶, —N(R¹⁵)S(O)₂R¹⁶, —CH₂—N(R¹⁵)S(O)₂R¹⁶, —N(R¹⁵)S(O)₂N(R¹⁶)(R¹⁷), —N(R¹⁵)S(O)N(R¹⁶)(R¹⁷), —N(R¹⁵)C(O)N(R¹⁶)(R¹⁷), —CH₂—N(R¹⁵)C(O)N(R¹⁶)(R¹⁷), —N(R¹⁵)C(O)OR¹⁶, —CH₂—N(R¹⁵)C(O)OR¹⁶, —S(O)R¹⁵, ═NOR¹⁵, —N₃, —NO₂ and —S(O)₂R¹⁵; and wherein each of the alkyl, cycloalkenyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, alkenyl and alkynyl groups in R²¹ are independently unsubstituted or substituted by 1 to 5 R²² groups independently selected from the group consisting of alkyl, cycloalkyl, cycloalkenyl, heterocycloalkyl, aryl, heteroaryl, halo, —CF₃, —CN, —OR¹⁵, —C(O)R¹⁵, —C(O)OR¹⁵, -alkyl-C(O)OR¹⁵, C(O)N(R¹⁵)(R¹⁶), —SR¹⁵, ^(—)S(O)N(R¹⁵)(R¹⁶), —S(O)₂N(R¹⁵)(R¹⁶), —C(═NOR¹⁵)R¹⁶, —P(O)(OR¹⁵)(OR¹⁶), —N(R¹⁵)(R¹⁶), -alkyl-N(R¹⁵)(R¹⁶), —N(R¹⁵)C(O)R¹⁶, —CH₂—N(R¹⁵)C(O)R¹⁶, —N(R¹⁵)S(O)R¹⁶, —N(R¹⁵)S(O)₂R¹⁶, —CH₂—N(R¹⁵)S(O)₂R¹⁶, —N(R¹⁵)S(O)₂N(R¹⁶)(R¹⁷), —N(R¹⁵)S(O)N(R¹⁶)(R¹⁷), —N(R¹⁵)C(O)N(R¹⁶)(R¹⁷), —CH₂—N(R¹⁵)C(O)N(R¹⁶)(R¹⁷), —N(R¹⁵)C(O)OR¹⁶, —CH₂—N(R¹⁵)C(O)OR¹⁶, —N₃, ═NOR¹⁵, —NO₂, —S(O)R¹⁵ and —S(O)₂R¹⁵;

or two R²¹ or two R²² moieties on adjacent carbons can be linked together to form

and when R²¹ or R²² are selected from the group consisting of —C(═NOR¹⁵)R¹⁶, —N(R¹⁵)C(O)R¹⁶, —CH₂—N(R¹⁵)C(O)R¹⁶, —N(R¹⁵)S(O)R¹⁶, —N(R¹⁵)S(O)₂R¹⁶, —CH₂—N(R¹⁵)S(O)₂R¹⁶, —N(R¹⁵)S(O)₂N(R¹⁶)(R¹⁷), —N(R¹⁵)S(O)N(R¹⁶)(R¹⁷), —N(R¹⁵)C(O)N(R¹⁶)(R¹⁷), —CH₂—N(R¹⁵)C(O)N(R¹⁶)(R¹⁷), —N(R¹⁵)C(O)OR¹⁶ and —CH₂—N(R¹⁵)C(O)OR¹⁶, R¹⁵ and R¹⁶ together can be a C₂ to C₄ chain wherein, optionally, one, two or three ring carbons can be replaced by —C(O)— or —N(H)— and R¹⁵ and R¹⁶, together with the atoms to which they are attached, form a 5 to 7 membered ring, optionally substituted by R²³;

R²³ is 1 to 5 groups independently selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, halo, —CN, —OR²⁴, —C(O)R²⁴, —C(O)OR²⁴, —C(O)N(R²⁴)(R²⁵), —SR²⁴, —S(O)₂N(R²⁴)(^(R25)), —C(═NOR²⁴)R²⁵, —P(O)(OR²⁴)(OR²⁵), —N(r²⁴)(R²⁵), -alkyl-N(R²⁴)(R²⁵), —N(R²⁴)C(O)R²⁵, —CH₂—N(R²⁴)C(O)R²⁵, —N(R²⁴)S(O)R²⁵, —N(R²⁴)S(O)₂R²⁵, —CH₂—N(R²⁴)S(O)₂R²⁵, —N(R²⁴)S(O)₂N(R²⁵)(R²⁶), —N(R²⁴)S(O)N(R²⁵)(R²⁶), —N(R²⁴)C(O)N(R²⁵)(R²⁶), —CH₂—N(R²⁴)C(O)N(R²⁵)(R²⁶), —N(R²⁴)C(O)OR²⁵, —CH₂—N(R²⁴)C(O)OR²⁵, —S(O)R²⁴ and —S(O)₂R²⁴; and wherein each of the alkyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, alkenyl and alkynyl groups in R²³ are independently unsubstituted or substituted by 1 to 5 R²⁷ groups independently selected from the group consisting of alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, halo, —CF₃, —CN, —OR²⁴, —C(O)R²⁴, —C(O)OR²⁴, -alkyl-C(O)OR²⁴, —C(O)N(R²⁴)(R²⁵), —SR²⁴, —S(O)N(R²⁴)(R²⁵), —S(O)₂N(R²⁴)(R²⁵), —C(═NOR²⁴) R²⁵, —P(O)(OR²⁴)(OR²⁵), —N(R²⁴)(R²⁵), -alkyl-N(R²⁴)(R²⁵), —N(R²⁴)C(O)R²⁵, —N(R²⁴)S(O)₂R²⁵, —CH₂—N(R²⁴)S(O)₂R²⁵, —CH₂—N(R²⁴)C(O)R²⁵, —N(R²⁴)S(O)R²⁵, —N(R²⁴)S(O)₂N(R²⁵)(R²⁶), —N(R²⁴)S(O)N(R²⁵)(R²⁶), —N(R²⁴)C(O)N(R²⁵)(R²⁶), —CH₂—N(R²⁴)C(O)N(R²⁵)(R²⁶), —N(R²⁴)C(O)OR²⁵, —CH₂—N(R²⁴)C(O)OR²⁵, —S(O)R²⁴ and —S(O)₂R²⁴;

R²⁴, R²⁵ and R²⁶ are independently selected from the group consisting of H, alkyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, arylcycloalkyl, R²⁷-alkyl, R²⁷-cycloalkyl, R²⁷-cycloalkylalkyl, R²⁷-heterocycloalkyl, R²⁷-heterocycloalkylalkyl, R²⁷-aryl, R²⁷-arylalkyl, R²⁷-heteroaryl and R²⁷-heteroarylalkyl;

R²⁷ is 1-5 substituents independently selected from the group consisting of alkyl, aryl, arylalkyl, —NO₂, halo, —CF₃, —CN, alkyl-CN, —C(O)R²⁸, —C(O)OH, —C(O)OR²⁸, —C(O)NHR²⁹, —C(O)N(alkyl)₂, —C(O)N(alkyl)(aryl), —C(O)N(alkyl)(heteroaryl), —SR²⁸, —S(O)₂R²⁹, —S(O)NH₂, —S(O)NH(alkyl), —S(O)N(alkyl)(alkyl), —S(O)NH(aryl), —S(O)₂NH₂, —S(O)₂NHR²⁸, —S(O)₂NH(aryl), —S(O)₂NH(heterocycloalkyl), —S(O)₂N(alkyl)₂, —S(O)₂N(alkyl)(aryl), —OH, —OR²⁹, —O-heterocycloalkyl, —O-cycloalkylalkyl, —O-heterocycloalkylalkyl, —NH₂, —NHR²⁹, —N(alkyl)₂, —N(arylalkyl)₂, —N(arylalkyl)(heteroarylalkyl), —NHC(O)R²⁹, —NHC(O)NH₂, —NHC(O)NH(alkyl), —NHC(O)N(alkyl)(alkyl), —N(alkyl)C(O)NH(alkyl), —N(alkyl)C(O)N(alkyl)(alkyl), —NHS(O)₂R²⁹, —NHS(O)₂NH(alkyl), —NHS(O)₂N(alkyl)(alkyl), —N(alkyl)S(O)₂NH(alkyl) and —N(alkyl)S(O)₂N(alkyl)(alkyl);

R²⁸ is alkyl, cycloalkyl, arylalkyl or heteroarylalkyl; and

R²⁹ is alkyl, cycloalkyl, aryl, arylalkyl, heteroaryl or heteroarylalkyl.

In another aspect, the invention relates to a pharmaceutical composition comprising at least one compound of formula I and a pharmaceutically acceptable carrier.

In another aspect, the invention comprises the method of inhibiting aspartyl proteases comprising administering at least one compound of formula I to a patient in need of such treatment.

More specifically, the invention comprises: the method of treating a cardiovascular disease such as hypertension, renal failure, congestive heart failure or another disease modulated by renin inhibition; the method of treating Human Immunodeficiency Virus; the method of treating a cognitive or neurodegenerative disease such as Alzheimer's Disease; the method of inhibiting plasmepsins I and II for treatment of malaria; the method of inhibiting Cathepsin D for the treatment of Alzheimer's Disease, breast cancer, and ovarian cancer; and the method of inhibiting protozoal enzymes, for example inhibition of plasmodium falciparnum, for the treatment of fungal infections. Said method of treatment comprise administering at least one compound of formula I to a patient in need of such treatment. In particular, the invention comprises the method of treating Alzheimer's Disease comprising administering at least one compound of formula I to a patient in need of such treatment.

In another aspect, the invention comprises the method of treating Alzheimer's Disease comprising administering to a patient in need of such treatment a combination of at least one compound of formula I and a cholinesterase inhibitor or a muscarinic m₁ agonist or m₂ antagonist.

In a final aspect, the invention relates to a kit comprising in separate containers in a single package pharmaceutical compositions for use in combination, in which one container comprises a compound of formula I in a pharmaceutically acceptable carrier and a second container comprises a cholinesterase inhibitor or a muscarinic m₁ agonist or m₂ antagonist in a pharmaceutically acceptable carrier, the combined quantities being an effective amount to treat a cognitive disease or neurodegenerative disease such as Alzheimer's Disease.

DETAILED DESCRIPTION

Preferred compounds of formula I are

Alternatively, another group of preferred compounds of formula I are those compounds wherein R¹ is alkyl, heterocycloalkyl or heterocycloalkylalkyl.

Another group of preferred compounds of formula I are those compounds wherein R² is H or alkyl.

Another group of preferred compounds of formula I are those compounds wherein R³ is aryl, heteroaryl, alkyl, cycloalkyl or cycloalkylalkyl.

More preferred compounds of the invention are those compounds of formula I, wherein R⁴ is alkyl.

More preferred compounds of the invention are those compounds of formula I, wherein R⁵ is hydrogen.

More preferred compounds of the invention are those compounds of formula I, wherein Ar is arylene or heteroarylene.

More preferred compounds of the invention are those compounds of formula wherein W is —C(O)—, —S(O)₂—, —N(R⁵)—, —O—, —P(O)(OR¹⁵)— or —C═(NR⁵)—.

Another group of preferred compounds of formula I are those compounds wherein Ar is phenylene,

Another group of preferred compounds of formula I are those compounds wherein R¹⁴ is aryl, heteroaryl, alkyl, cycloalkyl or cycloalkylalkyl.

Another group of preferred compounds of formula I are those compounds wherein R³ is aryl-substituted aryl, heteroaryl-substituted aryl, aryl-substituted heteroaryl or heteroaryl-substituted heteroaryl, aryl-substituted cycloalkyl, heteroaryl-substituted cycloalkyl, aryl-substituted alkyl, heteroaryl-substituted alkyl, aryl-substituted cycloalkyl or , heteroaryl-substituted cycloalkylalkyl. More specifically, preferred compounds of formula I are those compounds where R³ is

In yet another group of preferred compounds of formula I are those compounds wherein

R¹ is alkyl, heterocycloalkyl or heterocycloalkylalkyl;

R² is H or alkyl;

R³ is aryl, heteroaryl, alkyl, cycloalkyl or cycloalkylalkyl;

R⁴ is alkyl;

R⁵ is hydrogen;

Ar is arylene or heteroarylene; and

W is —C(O)—, —S(O)₂—, —N(R⁵)—, —O—, —P(O)(OR¹⁵)— or —C═(NR⁵)—.

In yet another group of preferred compounds of formula I are those compounds wherein selected from the group consisting of

It is noted that the carbons of formula I may be replaced with 1 to 3 silicon atoms so long as all valency requirements are satisfied.

As used above, and throughout the specification, the following terms, unless otherwise indicated, shall be understood to have the following meanings:

“Patient” includes both human and animals.

“Mammal” means humans and other mammalian animals.

“Alkyl” means an aliphatic hydrocarbon group which may be straight or branched and comprising about 1 to about 20 carbon atoms in the chain. Preferred alkyl groups contain about 1 to about 12 carbon atoms in the chain. More preferred alkyl groups contain about 1 to about 6 carbon atoms in the chain. Branched means that one or more lower alkyl groups such as methyl, ethyl or propyl, are attached to a linear alkyl chain. “Lower alkyl” means a group having about 1 to about 6 carbon atoms in the chain which may be straight or branched. Non-limiting examples of suitable alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, n-pentyl, heptyl, nonyl and decyl.

“Alkenyl” means an aliphatic hydrocarbon group containing at least one carbon-carbon double bond and which may be straight or branched and comprising about 2 to about 15 carbon atoms in the chain. Preferred alkenyl groups have about 2 to about 12 carbon atoms in the chain; and more preferably about 2 to about 6 carbon atoms in the chain. Branched means that one or more lower alkyl groups such as methyl, ethyl or propyl, are attached to a linear alkenyl chain. “Lower alkenyl” means about 2 to about 6 carbon atoms in the chain which may be straight or branched. Non-limiting examples of suitable alkenyl groups include ethenyl, propenyl, n-butenyl, 3-methylbut-2-enyl, n-pentenyl, octenyl and decenyl.

“Alkynyl” means an aliphatic hydrocarbon group containing at least one carbon-carbon triple bond and which may be straight or branched and comprising about 2 to about 15 carbon atoms in the chain. Preferred alkynyl groups have about 2 to about 12 carbon atoms in the chain; and more preferably about 2 to about 4 carbon atoms in the chain. Branched means that one or more lower alkyl groups such as methyl, ethyl or propyl, are attached to a linear alkynyl chain. “Lower alkynyl” means about 2 to about 6 carbon atoms in the chain which may be straight or branched. Non-limiting examples of suitable alkynyl groups include ethynyl, propynyl, 2-butynyl, 3-methylbutynyl, n-pentynyl, and decynyl.

“Aryl” means an aromatic monocyclic or multicyclic ring system comprising about 6 to about 14 carbon atoms, preferably about 6 to about 10 carbon atoms. The aryl group can be optionally substituted with one or more substituents (e.g., R18, R21, R²², etc.) which may be the same or different, and are as defined herein or two substituents on adjacent carbons can be linked together to form

Non-limiting examples of suitable aryl groups include phenyl, naphthyl, indenyl, tetrahydronaphyl and indanyl.

“Heteroaryl” means an aromatic monocyclic or multicyclic ring system comprising about 5 to about 14 ring atoms, preferably about 5 to about 10 ring atoms, in which one to eight of the ring atoms is an element other than carbon, for example nitrogen, oxygen or sulfur, alone or in combination. Preferred heteroaryls contain about 5 to about 6 ring atoms. The “heteroaryl” can be optionally substituted by one or more R²¹ substituents which may be the same or different, and are as defined herein. The prefix aza, oxa or thia before the heteroaryl root name means that at least a nitrogen, oxygen or sulfur atom respectively, is present as a ring atom. A nitrogen atom of a heteroaryl can be optionally oxidized to the corresponding N-oxide. Non-limiting examples of suitable heteroaryls include pyridyl, pyrazinyl, furyl, furanyl, thienyl, pyrimidinyl, isoxazolyl, isothiazolyl, oxazolyl, thiazolyl, pyrazolyl, furazanyl, pyrrolyl, pyrazolyl, triazolyl, 1,2,4-thiadiazolyl, pyridazinyl, morpholinyl, quinoxalinyl, phthalazinyl, imidazo[1,2-a]pyridinyl, imidazo[2,1-b]thiazolyl, benzofurazanyl, benzofuranyl, indolyl, azaindolyl, benzimidazolyl, benzothienyl, quinolinyl, imidazolyl, thienopyridyl, quinazolinyl, thienopyrimidyl, pyrrolopyridyl, imidazopyridyl, benzodioxolyl, indolyl, isoquinolinyl, benzoazaindolyl, 1,2,4-triazinyl, benzothiazolyl and the like.

“Cycloalkyl” means a non-aromatic mono- or multicyclic ring system comprising about 3 to about 10 carbon atoms, preferably about 5 to about 10 carbon atoms. Preferred cycloalkyl rings contain about 5 to about 7 ring atoms. The cycloalkyl can be optionally substituted with one or more substituents which may be the same or different, and are as defined above. Non-limiting examples of suitable monocyclic cycloalkyls include cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl and the like. Non-limiting examples of suitable multicyclic cycloalkyls include 1-decalin, norbornyl, adamantyl and the like. Further non-limiting examples of cycloalkyl include the following

“Cycloalkylether” means a non-aromatic ring of 3 to 7 atoms comprising an oxygen atom and 2 to 6 carbon atoms. Ring carbon atoms can be substituted, provided that substituents adjacent to the ring oxygen do not include halo or substituents joined to the ring through an oxygen, nitrogen or sulfur atom.

“Cycloalkenyl” means a non-aromatic mono or multicyclic ring system comprising about 3 to about 10 carbon atoms, preferably about 5 to about 10 carbon atoms which contains at least one carbon-carbon double bond. The cycloalkenyl ring can be optionally substituted with one or more R²¹ substituents which may be the same or different, and are as defined above. Preferred cycloalkenyl rings contain about 5 to about 7 ring atoms. Non-limiting examples of suitable monocyclic cycloalkenyls include cyclopentenyl, cyclohexenyl, cycloheptenyl, and the like. Non-limiting example of a suitable multicyclic cycloalkenyl is norbornylenyl.

“Heterocyclenyl” means a non-aromatic monocyclic or multicyclic ring system comprising about 3 to about 14 ring atoms, preferably about 5 to about 10 ring atoms, in which one or more of the atoms in the ring system is an element other than carbon, for example nitrogen, oxygen or sulfur atom, alone or in combination, and which contains at least one carbon-carbon double bond or carbon-nitrogen double bond.

There are no adjacent oxygen and/or sulfur atoms present in the ring system. Preferred heterocyclenyl rings contain about 5 to about 6 ring atoms. The prefix aza, oxa or thia before the heterocyclenyl root name means that at least a nitrogen, oxygen or sulfur atom respectively is present as a ring atom. The heterocyclenyl can be optionally substituted by one or more R²¹ substituents which may be the same or different. The nitrogen or sulfur atom of the heterocyclenyl can be optionally oxidized to the corresponding N-oxide, S-oxide or S,S-dioxide. Non-limiting examples of suitable monocyclic azaheterocyclenyl groups include 1,2,3,4- tetrahydropyridyl, 1,2-dihydropyridyl, 1,4-dihydropyridyl, 1,2,3,6-tetrahydropyridyl, 1,4,5,6-tetrahydropyrimidyl, 2-pyrrolinyl, 3-pyrrolinyl, 2-imidazolinyl, 2-pyrazolinyl, and the like.

Non-limiting examples of suitable oxaheterocyclenyl groups include 3,4-dihydro-2H-pyran, dihydrofuranyl, fluorodihydrofuranyl, and the like. Non-limiting example of a suitable multicyclic oxaheterocyclenyl group is 7-oxabicyclo[2.2.1]heptenyl. Non-limiting examples of suitable monocyclic thiaheterocyclenyl rings include dihydrothiophenyl, dihydrothiopyranyl, and the like.

“Halo” means fluoro, chloro, bromo, or iodo groups. Preferred are fluoro, chloro or bromo, and more preferred are fluoro and chloro.

“Haloalkyl” means an alkyl as defined above wherein one or more hydrogen atoms on the alkyl is replaced by a halo group defined above.

“Heterocyclyl” (or heterocycloalkyl) means a non-aromatic saturated monocyclic or multicyclic ring system comprising about 3 to about 10 ring atoms, preferably about 5 to about 14 ring atoms, in which 1-3, preferably 1 or 2 of the atoms in the ring system is an element other than carbon, for example nitrogen, oxygen or sulfur, alone or in combination. There are no adjacent oxygen and/or sulfur atoms present in the ring system. Preferred heterocyclyls contain about 5 to about 6 ring atoms. The prefix aza, oxa or thia before the heterocyclyl root name means that at least a nitrogen, oxygen or sulfur atom respectively is present as a ring atom. The heterocyclyl can be optionally substituted by one or more R²¹ substituents which may be the same or different, and are as defined herein. The nitrogen or sulfur atom of the heterocyclyl can be optionally oxidized to the corresponding N-oxide, S-oxide or S,S-dioxide. Non-limiting examples of suitable monocyclic heterocyclyl rings include piperidyl, pyrrolidinyl, piperazinyl, morpholinyl, thiomorpholinyl, thiazolidinyl, 1,3-dioxolanyl, 1,4-dioxanyl, tetrahydrofuranyl, tetrahydrothiophenyl, tetrahydrothiopyranyl, and the like.

“Arylalkyl” means an aryl-alkyl- group in which the aryl and alkyl are as previously described. Preferred aralkyls comprise a lower alkyl group. Non-limiting examples of suitable aralkyl groups include benzyl, 2-phenethyl and naphthamethyl. The bond to the parent moiety is through the alkyl.

“Arylcycloalkyl” means a group derived from a fused aryl and cycloalkyl as defined herein. Preferred arylcycloalkyls are those wherein aryl is phenyl and cycloalkyl consists of about 5 to about 6 ring atoms. The arylcycloalkyl can be optionally substituted by 1-5 R²¹ substituents. Non-limiting examples of suitable arylcycloalkyls include indanyl and 1,2,3,4-tetrahydronaphthyl and the like. The bond to the parent moiety is through a non-aromatic carbon atom.

“Arylheterocycloalkyl” means a group derived from a fused aryl and heterocycloalkyl as defined herein. Preferred arylcycloalkyls are those wherein aryl is phenyl and heterocycloalkyl consists of about 5 to about 6 ring atoms. The arylheterocycloalkyl can be optionally substituted by 1-5 R²¹ substituents. Non-limiting examples of suitable arylheterocycloalkyls include

The bond to the parent moiety is through a non-aromatic carbon atom. Similarly, “heteroarylalkyl” “cycloalkylalkyl” and “heterocycloalkylalkyl” mean a heteroaryl-, cycloalkyl- or heterocycloalkyl-alkyl- group in which the heteroaryl, cycloalkyl, heterocycloalkyl and alkyl are as previously described. Preferred groups contain a lower alkyl group. The bond to the parent moiety is through the alkyl.

“Acyl” means an H—C(O)—, alkyl-C(O)—, alkenyl-C(O)—, alkynyl-C(O)— or cycloalkyl-C(O)— group in which the various groups are as previously described. The bond to the parent moiety is through the carbonyl. Preferred acyls contain a lower alkyl. Non-limiting examples of suitable acyl groups include formyl, acetyl, propanoyl, 2-methylpropanoyl, butanoyl and cyclohexanoyl.

“Alkoxy” means an alkyl-O— group in which the alkyl group is as previously described. Non-limiting examples of suitable alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy and heptoxy. The bond to the parent moiety is through the ether oxygen.

“Alkoxyalkyl” means a group derived from an alkoxy and alkyl as defined herein. The bond to the parent moiety is through the alkyl.

“Arylalkenyl” means a group derived from an aryl and alkenyl as defined herein. Preferred arylalkenyls are those wherein aryl is phenyl and the alkenyl consists of about 3 to about 6 atoms. The arylalkenyl can be optionally substituted by one or more R²⁷ substituents. The bond to the parent moiety is through a non-aromatic carbon atom.

“Arylalkynyl” means a group derived from a aryl and alkynyl as defined herein. Preferred arylalkynyls are those wherein aryl is phenyl and the alkynyl consists of about 3 to about 6 atoms. The arylalkynyl can be optionally substituted by one or more R²⁷ substituents. The bond to the parent moiety is through a non-aromatic carbon atom.

The suffix “ene” on alkyl, aryl, hetercycloalkyl, etc. indicates a divalent moiety, e.g., —CH₂CH₂— is ethylene, and

is para-phenylene.

It is understood that multicyclic divalent groups, for example, arylheterocycloalkylene, can be attached to other groups via bonds that are formed on either ring of said group. For example,

The term “optionally substituted” means optional substitution with the specified groups, radicals or moieties, in available position or positions.

Substitution on a cycloalkylalkyl, heterocycloalkylalkyl, arylalkyl, or heteroarylalkyl moiety includes substitution on the ring portion and/or on the alkyl portion of the group.

When a variable appears more than once in a group, or a variable appears more than once in the structure of formula I, e.g., R⁵ may appear in both U and W, the variables can be the same or different.

With reference to the number of moieties (e.g., substituents, groups or rings) in a compound, unless otherwise defined, the phrases “one or more” and “at least one” mean that there can be as many moieties as chemically permitted, and the determination of the maximum number of such moieties is well within the knowledge of those skilled in the art. With respect to the compositions and methods comprising the use of “at least one compound of formula I,” one to three compounds of formula I can be administered at the same time, preferably one.

As used herein, the term “composition” is intended to encompass a product comprising the specified ingredients in the specified amounts, as well as any product which results, directly or indirectly, from combination of the specified ingredients in the specified amounts.

The wavy line

as a bond generally indicates a mixture of, or either of, the possible isomers, e.g., containing (R)- and (S)-stereochemistry. For example,

means containing both

Lines drawn into the ring systems, such as, for example:

indicate that the indicated line (bond) may be attached to any of the substitutable ring carbon atoms.

As well known in the art, a bond drawn from a particular atom wherein no moiety is depicted at the terminal end of the bond indicates a methyl group bound through that bond to the atom, unless stated otherwise. For example:

represents

It should also be noted that any heteroatom with unsatisfied valences in the text, schemes, examples, structural formulae, and any Tables herein is assumed to have the hydrogen atom or atoms to satisfy the valences.

Those skilled in the art will recognize that certain compounds of formula I are tautomeric, and all such tautomeric forms are contemplated herein as part of the present invention.

Prodrugs and solvates of the compounds of the invention are also contemplated herein. A discussion of prodrugs is provided in T. Higuchi and V. Stella, Pro-drugs as Novel Delivery Systems (1987) 14 of the A.C.S. Symposium Series, and in Bioreversible Carriers in Drug Design, (1987) Edward B. Roche, ed., American Pharmaceutical Association and Pergamon Press. The term “prodrug” means a compound (e.g, a drug precursor) that is transformed in vivo to yield a compound of Formula (I) or a pharmaceutically acceptable salt, hydrate or solvate of the compound. The transformation may occur by various mechanisms (e.g., by metabolic or chemical processes), such as, for example, through hydrolysis in blood. A discussion of the use of prodrugs is provided by T. Higuchi and W. Stella, “Pro-drugs as Novel Delivery Systems,” Vol. 14 of the A.C.S. Symposium Series, and in Bioreversible Carriers in Drug Design, ed. Edward B. Roche, American Pharmaceutical Association and Pergamon Press, 1987.

For example, if a compound of Formula (I) or a pharmaceutically acceptable salt, hydrate or solvate of the compound contains a carboxylic acid functional group, a prodrug can comprise an ester formed by the replacement of the hydrogen atom of the acid group with a group such as, for example, (C₁-C₈)alkyl, (C₂-C₁₂)alkanoyloxymethyl, 1-(alkanoyloxy)ethyl having from 4 to 9 carbon atoms, 1-methyl-1-(alkanoyloxy)-ethyl having from 5 to 10 carbon atoms, alkoxycarbonyloxymethyl having from 3 to 6 carbon atoms, 1-(alkoxycarbonyloxy)ethyl having from 4 to 7 carbon atoms, 1-methyl-1-(alkoxycarbonyloxy)ethyl having from 5 to 8 carbon atoms, N-(alkoxycarbonyl)aminomethyl having from 3 to 9 carbon atoms, 1-(N-(alkoxycarbonyl)amino)ethyl having from 4 to 10 carbon atoms, 3-phthalidyl, 4-crotonolactonyl, gamma-butyrolacton-4-yl, di-N,N—(C₁-C₂)alkylamino(C₂-C₃)alkyl (such as β-dimethylaminoethyl), carbamoyl-(C₁-C₂)alkyl, N,N-di (C₁-C₂)alkylcarbamoyl-(C₁-C₂)alkyl and piperidino-, pyrrolidino- or morpholino(C₂-C₃)alkyl, and the like.

Similarly, if a compound of Formula (I) contains an alcohol functional group, a prodrug can be formed by the replacement of the hydrogen atom of the alcohol group with a group such as, for example, (C₁-C₆)alkanoyloxymethyl, 1-((C₁-C₆)alkanoyloxy)ethyl, 1-methyl-1-((C₁-C₆)alkanoylm)ethyl, (C₁-C₆)alkoxycarbonyloxymethyl, N—(C₁-C₆)alkoxycarbonylaminomethyl, succinoyl, (C₁-C₆)alkanoyl, α-amino(C₁-C₄)alkanyl, arylacyl and α-aminoacyl, or α-aminoacyl-α-aminoacyl, where each α-aminoacyl group is independently selected from the naturally occurring L-amino acids, P(O)(OH)₂, —P(O)(O(C₁-C₆)alkyl)₂ or glycosyl (the radical resulting from the removal of a hydroxyl group of the hemiacetal form of a carbohydrate), and the like.

If a compound of Formula (I) incorporates an amine functional group, a prodrug can be formed by the replacement of a hydrogen atom in the amine group with a group such as, for example, R-carbonyl, RO-carbonyl, NRR′-carbonyl where R and R′ are each independently (C₁-C₁₀)alkyl, (C₃-C₇) cycloalkyl, benzyl, or R-carbonyl is a natural α-aminoacyl or natural α-aminoacyl, —C(OH)C(O)OY¹ wherein Y¹ is H, (C₁-C₆)alkyl or benzyl, —C(OY²)Y³ wherein Y² is (C₁-C₄) alkyl and Y³ is (C_(i)-C₆)alkyl, carboxy (C₁-C₆)alkyl, amino(C₁-C₄)alkyl or mono-N— or di-N,N—(C₁-C₆)alkylaminoalkyl, —C(Y⁴)Y⁵ wherein Y⁴ is H or methyl and Y⁵ is mono-N— or di-N,N—(C₁-C₆)alkylamino morpholino, piperidin-1-yl or pyrrolidin-1-yl, and the like.

“Solvate” means a physical association of a compound of this invention with one or more solvent molecules. This physical association involves varying degrees of ionic and covalent bonding, including hydrogen bonding. In certain instances the solvate will be capable of isolation, for example when one or more solvent molecules are incorporated in the crystal lattice of the crystalline solid. “Solvate” encompasses both solution-phase and isolatable solvates. Non-limiting examples of suitable solvates include ethanolates, methanolates, and the like. “Hydrate” is a solvate wherein the solvent molecule is H₂O.

“Effective amount” or “therapeutically effective amount” is meant to describe an amount of compound or a composition of the present invention effective in inhibiting aspartyl protease and/or inhibiting BACE-1 and thus producing the desired therapeutic effect in a suitable patient.

The compounds of formula I form salts which are also within the scope of this invention. Reference to a compound of formula I herein is understood to include reference to salts thereof, unless otherwise indicated. The term “salt(s)”, as employed herein, denotes acidic salts formed with inorganic and/or organic acids, as well as basic salts formed with inorganic and/or organic bases. In addition, when a compound of formula I contains both a basic moiety, such as, but not limited to a pyridine or imidazole, and an acidic moiety, such as, but not limited to a carboxylic acid, zwitterions (“inner salts”) may be formed and are included within the term “salt(s)” as used herein. Pharmaceutically acceptable (i.e., non-toxic, physiologically acceptable) salts are preferred, although other salts are also useful. Salts of the compounds of the formula I may be formed, for example, by reacting a compound of formula I with an amount of acid or base, such as an equivalent amount, in a medium such as one in which the salt precipitates or in an aqueous medium followed by lyophilization. Acids (and bases) which are generally considered suitable for the formation of pharmaceutically useful salts from basic (or acidic) pharmaceutical compounds are discussed, for example, by S. Berge et al, Journal of Pharmaceutical Sciences (1977) 66(1) 1-19; P. Gould, International J. of Pharmaceutics (1986) 33 201-217; Anderson et al, The Practice of Medicinal Chemistry (1996), Academic Press, New York; in The Orange Book (Food & Drug Administration, Washington, D.C. on their website); and P. Heinrich Stahl, Camille G. Wermuth (Eds.), Handbook of Pharmaceutical Salts: Properties, Selection, and Use, (2002) Intl. Union of Pure and Applied Chemistry, pp. 330-331. These disclosures are incorporated herein by reference thereto.

Exemplary acid addition salts include acetates, adipates, alginates, ascorbates, aspartates, benzoates, benzenesulfonates, bisulfates, borates, butyrates, citrates, camphorates, camphorsulfonates, cyclopentanepropionates, digluconates, dodecylsulfates, ethanesulfonates, fumarates, glucoheptanoates, glycerophosphates, hemisulfates, heptanoates, hexanoates, hydrochlorides, hydrobromides, hydroiodides, 2-hydroxyethanesulfonates, lactates, maleates, methanesulfonates, methyl sulfates, 2-naphthalenesulfonates, nicotinates, nitrates, oxalates, pamoates, pectinates, persulfates, 3-phenylpropionates, phosphates, picrates, pivalates, propionates, salicylates, succinates, bisulfates, sulfates, sulfonates (such as those mentioned herein), tartarates, thiocyanates, toluenesulfonates (also known as tosylates,) undecanoates, and the like.

Exemplary basic salts include ammonium salts, alkali metal salts such as sodium, lithium, and potassium salts, alkaline earth metal salts such as calcium and magnesium salts, aluminum salts, zinc salts, salts with organic bases (for example, organic amines) such as benzathines, diethylamine, dicyclohexylamines, hydrabamines (formed with N,N-bis(dehydroabietyl)ethylenediamine), N-methyl-D-glucamines, N-methyl-D-glucamides, t-butyl amines, piperazine, phenylcyclohexylamine, choline, tromethamine, and salts with amino acids such as arginine, lysine and the like. Basic nitrogen-containing groups may be quarternized with agents such as lower alkyl halides (e.g. methyl, ethyl, propyl, and butyl chlorides, bromides and iodides), dialkyl sulfates (e.g. dimethyl, diethyl, dibutyl, and diamyl sulfates), long chain halides (e.g. decyl, lauryl, myristyl and stearyl chlorides, bromides and iodides), aralkyl halides (e.g. benzyl and phenethyl bromides), and others.

All such acid salts and base salts are intended to be pharmaceutically acceptable salts within the scope of the invention and all acid and base salts are considered equivalent to the free forms of the corresponding compounds for purposes of the invention.

All stereoisomers (for example, geometric isomers, optical isomers and the like) of the present compounds (including those of the salts, solvates and prodrugs of the compounds as well as the salts and solvates of the prodrugs), such as those which may exist due to asymmetric carbons on various substituents, including enantiomeric forms (which may exist even in the absence of asymmetric carbons), rotameric forms, atropisomers, and diastereomeric forms, are contemplated within the scope of this invention. Individual stereoisomers of the compounds of the invention may, for example, be substantially free of other isomers, or may be admixed, for example, as racemates or with all other, or other selected, stereoisomers. The chiral centers of the present invention can have the S or R configuration as defined by the IUPAC 1974 Recommendations. The use of the terms “salt”, “solvate”, “prodrug” and the like, is intended to equally apply to the salt, solvate and prodrug of enantiomers, stereoisomers, rotamers, tautomers, racemates or prodrugs of the inventive compounds.

Polymorphic forms of the compounds of formula I, and of the salts, solvates and prodrugs of the compounds of formula I, are intended to be included in the present invention

Compounds of formula I can be made using procedures known in the art. The following reaction schemes show typical procedures, but those skilled in the art will recognize that other procedures can also be suitable.

In the Schemes and in the Example below, the following abbreviations are used:

DCM: dichloromethane;

EtOAc: ethyl acetate

TEA: triethylamine

eq: equivalent

Boc: tert-butoxycarbonyl

h or hr: hour

DMF: N,N-dimethylformamide

NBS: N-bromosuccinimide

DDQ: 2,3-dichloro-5,6-dicyano-1,4- benzoquinone

TFA: trifluoroacetic acid

THF: Tetrahydrofuran

LiHMDS: lithium bis(trimethylsilyl)amide

r.t. or R.T.: room temperature

sat. or sat'd: saturated

Bu₂Mg: dibutylmagnesium

SM: starting material

HOBT: 1-hydroxybenzotriazole

DIEA: N, N-diisopropylethylamine

EDCI.HCl: 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride

Mel: methyl iodide

Pd(PPh₃)₄: tetrakis (Triphenylphosphine) Palladium

Rh₂(OAc)₄: Rhodium (II) acetate

PhI(OAc)₂: lodobenzene diacetate

Cbz: benzyloxycarbonyl

DMF.DMA: N,N-dimethylformamide dimethylacetyl

Bt: benzotriazole

MeNH₂: methylamine

(Boc)₂O: Di-tert-butyl dicarbonate

Pd(OAc)2: Palladium acetate

P(tBu)₃: tri-tert-butylphosphine

Selected examples:

Method A, Step 1;

A literature procedure is adapted (Lenz, George R.; Costanza, Carl; Lessor, Ralph A.; Ezell, Edward F Journal of Organic Chemistry (1990), 55(6), 1753-7). A solution of A1 and A2 (1 eq) in anhydrous ether is treated with activated 4 Å molecular sieves (1 g/mmol) for 3 days. After removal of molecular sieves and solvent, the residue is distilled under vacuum to give the desired product A3.

Method A, Step 2;

To an ethereal solution of compound A3 is added 2-thienyl Grignard reagent (1.1 eq) at −78° C. The solution is warmed-up to r.t. Quench solution with sat. aq. sodium carbonate and extract with DCM. The organic solution is dried and solvent evaporated to give a residue, which is chromatographed using EtOAc/Hexane (0.1% TEA) to give product A4.

Method A, Step 3

Literature procedures are adapted for this transformation. a) Siddiqui, Salimuzzaman; Haider, S. lmtiaz; Ahmad, S. Salman; Siddiqui, B. Shaheen. Zeitschrift fuer Naturforschung, Tell B: Anorganische Chemie, Organische Chemie (1985), 40B(4), 546-9; b) Zahariev, Sotir; Guarnaccia, Corrado; Lamba, Doriano; Cemazar, Masa; Pongor, Sandor. Tetrahedron Letters (2004), 45(51), 9423-9426

To a cooled solution of A4 in DCM at 0° C., is added cyanogen bromide (1 eq) and the solution is let warm up to r.t. until the starting material is gone. After the solvent is evaporated, the residue is heated using a microwave oven with 1 eq of the benzotriazole hydrochloride to 80° C. for five min. in a sealed tube before Methylamine (0.5 eq) and triethylamine (1 eq) in acetonitrile is added and the mixture is sealed in the tube and heated at 60° C. overnight. After the reaction mixture is partitioned between DCM/sat. aq Na₂CO₃, the organic layer is dried and concentrated. The residue is treated with Boc anhydride (1 eq) in DCM and the reaction stirred for 4 h. before it is partitioned between DCM/NaHCO₃. The organic layer is dried and concentrated and the residue is chromatographed to give product A5.

Method A, Step 4

A literature procedure is adapted (G. Bocelli, M. Catellani, F. Cugini and R. Ferraccioli, Tetrahedron Lett. 1999, 40, 2623-2624.)

To a DMF solution of compound AS in a sealable tube is added palladium tetrakis(triphenylphosphine) and purged with CO gas. The reaction mixture is heated at 80° C. for 2 h before the reaction mixture is partitioned between DCM/water. The organic layer is concentrated and residue chromatographed to give product A6.

Method A, Step 5.

Compound A6 is treated with NBS (1 eq) in DCM overnight to give product A7 after purification.

Method A, Step 6.

Compound A7, p-fluoro-m-cyanophenyl boronic acid (1.5 eq), Palladium tetrakis(triphenylphosphine) (0.05 eq) and 1N aq K₂CO₃ (2 eq) in DMF is heated in a microwave oven at 90° C. under nitrogen for 5 min to give product A8 after purification.

Method A, Step 7

Compound A8 was treated with DDQ in acetonitrile to give product A9 after purification and TFA treatment.

Method B, Step 1;

A literature procedure is adapted (J. Mathew and B. Alink; J. Org. Chem. 1990, 55, 3880).

To a LiHMDS solution (1 eq) at −78° C. in THF is added ethyl acetate (1 eq) and the solution is stirred for 45 min before a THF solution of Compound B1, prepared using a known procedure (A. Robert, S. Jaguelin and et J. L. Guinamant; Tetrahedron 1986, 42 (8), 2275) is added. The solution is stirred at −70° C. for 30 min before it is warmed to r.t. The reaction is quenched using 1 N HCl and the mixture is extracted using ether/water. The organic solution is concentrated and residue chromatographed to give compound B2.

Method B, Step 2:

A literature procedure is adapted (R. Brechenridge and C. Suckling J. Chem. Research (S), 1982, 166)

To an ethanol solution of B2 is added with stirring a suspension of Boc-Guanidine. The mixture is stirred and heated under reflux for 6 h. before the reaction is cooled to r.t., solvent removed and residue partitioned between sat. NaHCO₃ and ether. The organic layers are dried and concentrated and residue chromatographed to give product B3.

Method B, Step 4.

A mixture of compound B3 in DMF dimethylacetal (10 eq) is heated to 80° C. for 2 h. before the solution is cooled to r.t. and volatiles evaporated. The residue is chromatographed to give product B4.

Method B, Step 5.

Compound B4 is mixed with m-CN-phenylboronic acid (1.5 eq), Pd(PPh₃)₄ (0.1 eq), sat. aq K₂CO₃ (2 eq) in DMF under nitrogen and the mixture is heated in a sealed tube at 100° C. for 5 min using a microwave oven. The solvent is evaporated and residue chromatographed to give compound B5.

Method B, Step 6.

Compound A5 is mixed with hydrazine (2 eq) in ethanol and mixture is heated to reflux for 3 h. before the solvent is removed and residue chromatographed to give a product, which is treated with TFA to give compound B6.

The following compounds can be synthesized using similar method:

Method C, Step 1

The procedure is adapted from the literature method (B.R. Linton et al., J. Org. Chem., 2000, 65, 1566).

Cool a solution of benzyloxycarbonyl isothiocyanate in CH₂Cl₂ to 0° C. and add A4 (1 equiv.). Remove the cooling bath and stir the reaction mixture at RT for 4 hr under an N₂ atmosphere. Wash the mixture with dilute HCl, water and brine, and dry the organic layer over Na₂SO₄. Remove the solvent under reduced pressure to give Cl which is used directly in the next step.

Method C, Step 2

To a solution of Cl in EtOH, add 1,2-dimethylhydrazine (2 equiv.) and stir the reaction mixture for 8 hr. Add sat'd NaHCO₃ and extract with CH₂Cl₂ (3×). Combine the CH₂Cl₂ extracts, dry over Na₂SO₄, filter and remove the solvent under reduced pressure. Subject the residue to silica gel chromatography to obtain C2.

Method C, Step 3

The procedure is adapted from the literature method (Y.K. Lim et al., J. Org. Chem., 2004, 69, 5778).

Heat a mixture of C2, Pd(OAc)₂ (5 mol %), P(tBu)₃ (5 mol %), and Cs₂CO₃ (1.5 equiv.) in toluene under an Ar atmosphere for 2 hr. Allow the reaction mixture to cool, concentrate under reduced pressure, and subject the residue to silica gel chromatography to give the product C3.

Method C, Step 4.

In analogy to Method A, Steps 5 and 6, convert C3 to C4.

Method C, Step 5.

Treat a mixture of C4 in methanol with 10% palladium-on-carbon (5 mol %) under an H₂ atmosphere for 16 hr. Filter the reaction mixture and concentrate the filtrate under reduced pressure. Subject the residue to silica gel chromatography to afford the product C5.

Method D, Step 1;

A literature procedure is adapted (S. Kato; N. Nonoyama; K. Tomimoto; T. Mase Tetrahedron Lett. 43 (2002), 7315-7317).

To a THF (10 ml) solution of D1 (5 mmol), cooled below to −15° C. under nitrogen , is added 1.0 M Bu₂Mg in heptane (0.52 eq) and the temperature is maintained under −5° C. Then n-BuLi in hexane (1.07 eq) is added and solution is stirred at −15° C. for 1 h.

to this solution is added D2 in heptane and the solution is stirred for 1 h before it is quenched with 2 N HCl (10 ml) and the mixture is stirred overnight. The solution is extracted with EtOAc and the organic layer washed with aq. NaHCO₃ and brine. After the solution is dried and solvent evaporated, the residue is chromatographed to give desired product D3.

Method D, Step 2;

To a DCM solution (10 ml) of D3 (5 mmol) is added triethylsilane (2 eq) and TFA (4 ml) and the solution is stirred until the SM disappears. The solution is evaporated to give product D4.

Method D, Step 3;

To a DMF (10 ml) solution of D4 (5 mmol) is added Boc-guanidine (1.0 eq), HOBt (1 eq), DIEA (eq) and EDCI.HCl (1.05 eq) and the solution is stirred overnight before the solution is partitioned between EtOAc/water. The organic layer is dried, solvent removed and the residue chromatographed to give desired product D5.

Method D, Step 4.

To a DMF solution (10 ml) of D5 (5 mmol) is added 1 ml saturated Na₂CO₃ and Mel (1.1 eq) and the reaction stirred overnight. After the solution is partitioned between EtOAc/water, the organic layer is dried, solvent removed and the residue chromatographed to give desired product D6.

Method D, Step 5.

A literature procedure is adapted (C. Espino and J. Du Bois; Angew. Chem. Int. Ed. 2001, 40, 598).

A mixture of D6 (5 mmol), Phl(OAc)₂ (1.4 eq), MgO (2.4 eq) and Rh₂(OAc)₄ (0.05%) is stirred at r.t. overnight to give product D7 after purification

Method D, Step 6.

A mixture of D7 (1 mmol) in 4 ml of DMF, m-Cyanophenylboronic acid (1.1 eq), sat. aq K₂CO₃ (2 eq) and Pd(PPh₃)₄ (10%) is heated under nitrogen to 100° C. for 10 min using a microwave oven. The reaction mixture is purified and the product is treated with 40% TFA in DCM to afford compound D8.

Human Cathepsin D FRET Assay

The substrate used below has been described (Y.Yasuda et al., J. Biochem., 125, 1137 (1999)). Substrate and enzyme are commercially available.

The assay can be run in a 30 μl final volume using a 384 well Nunc black plate. 8 concentrations of compound can be pre-incubated with enzyme for 30 mins at 37° C. followed by addition of substrate with continued incubation at 37° C. for 45 mins. The rate of increase in fluorescence is linear for over 1 h and is measured at the end of the incubation period using a Molecular Devices FLEX station plate reader. Kis are interpolated from the IC50s using a Km value of 4 μM and the substrate concentration of 2.5 μM.

Reagents

-   Na-Acetate pH 5 -   1% Brij-35 from 10% stock (Calbiochem) -   DMSO -   Purified (>95%) human liver Cathepsin D (Athens Research &     Technology Cat# 16-12-030104) -   Peptide substrate(Km=4uM)     Mca-Gly-Lys-Pro-Ile-Leu-Phe-Phe-Arg-Leu-Lys(Dnp)-D-Arg-NH₂ Bachem     Cat # M-2455 -   Pepstatin is used as a control inhibitor (Ki-0.5 nM) and is     available from Sigma. -   Nunc 384 well black plates     Final Assay buffer conditions -   100 mM Na Acetate pH 5.0 -   0.02% Brij-35 -   1% DMSO

Compound can be diluted to 3× final concentration in assay buffer containing 3% DMSO. 10 μl of compound will be added to 10 μl of 2.25 nM enzyme (3×) diluted in assay buffer without DMSO, mixed briefly, spun, and can be incubated at 37° C. for 30 mins. 3× substrate (7.5 μM) is prepared in 1× assay buffer without DMSO. 10 μl of substrate will be added to each well mixed and spun briefly to initiate the reaction. Assay plates can be incubated at 37 C for 45 mins and read on 384 compatible fluorescence plate reader using a 328 rim Ex and 393 nm Em.

BACE-1 Cloning, Protein Expression and Purification

A predicted soluble form of human BACE1 (sBACE1, corresponding to amino acids 1-454) can be generated from the full length BACE1 cDNA (full length human BACE1 cDNA in pCDNA4/mycHisA construct; University of Toronto) by PCR using the advantage-GC cDNA PCR kit (Clontech, Palo Alto, Calif.). A HindIII/Pmel fragment from pCDNA4-sBACE1 myc/His can be blunt ended using Klenow and subcloned into the Stu I site of pFASTBACI(A) (Invitrogen). A sBACE1mycHis recombinant bacmid can be generated by transposition in DH10Bac cells(GIBCO/BRL). Subsequently, the sBACE1mycHis bacmid construct can be transfected into sf9 cells using CellFectin (Invitrogen, San Diego, Calif.) in order to generate recombinant baculovirus. Sf9 cells are grown in SF 900-II medium (Invitrogen) supplemented with 3% heat inactivated FBS and 0.5× penicillin/streptomycin solution (Invitrogen). Five milliliters of high titer plaque purified sBACEmyc/His virus is used to infect 1L of logarithmically growing sf9 cells for 72 hours. Intact cells are pelleted by centrifugation at 3000 ×g for 15 minutes.

The supernatant, containing secreted sBACE1, is collected and diluted 50% v/v with 100 mM HEPES, pH 8.0. The diluted medium is loaded onto a Q-sepharose column. The Q-sepharose column is washed with Buffer A (20 mM HEPES, pH 8.0, 50 mM NaCl).

Proteins, can be eluted from the Q-sepharose column with Buffer B (20 mM HEPES, pH 8.0, 500 mM NaCl). The protein peaks from the Q-sepharose column are pooled and loaded onto a Ni-NTA agarose column. The Ni-NTA column can be then washed with Buffer C (20 mM HEPES, pH 8.0, 500 mM NaCl). Bound proteins are then eluted with Buffer D (Buffer C+250 mM imidazole). Peak protein fractions as determined by the Bradford Assay (Biorad, Calif.) are concentrated using a Centricon 30 concentrator (Millipore). sBACE1 purity is estimated to be ˜90% as assessed by SDS-PAGE and Commassie Blue staining. N-terminal sequencing indicates that greater than 90% of the purified sBACE1 contained the prodomain; hence this protein is referred to as sproBACE1.

Peptide Hydrolysis Assay

The inhibitor, 25 nM EuK-biotin labeled APPsw substrate (EuK-KTEEISEVNLDAEFRHDKC-biotin; CIS-Bio International, France), 5 μM unlabeled APPsw peptide (KTEEISEVNLDAEFRHDK; American Peptide Company, Sunnyvale, CA), 7 nM sproBACE1, 20 mM PIPES pH 5.0, 0.1% Brij-35 (protein grade, Calbiochem, San Diego, Calif.), and 10% glycerol are preincubated for 30 min at 30° C. Reactions are initiated by addition of substrate in a 5 μl aliquot resulting in a total volume of 25 After 3 hr at 30° C. reactions are terminated by addition of an equal volume of 2x stop buffer containing 50 mM Tris-HCl pH 8.0, 0.5 M KF, 0.001% Brij-35, 20 μg/ml SA-XL665 (cross-linked allophycocyanin protein coupled to streptavidin; CIS-Bio International, France) (0.5 μg/well). Plates are shaken briefly and spun at 1200 ×g for 10 seconds to pellet all liquid to the bottom of the plate before the incubation. HTRF measurements are made on a Packard Discovery® HTRF plate reader using 337 nm laser light to excite the sample followed by a 50 μs delay and simultaneous measurements of both 620 nm and 665 nm emissions for 400 μs.

IC₅₀ determinations for inhibitors, (I), are determined by measuring the percent change of the relative fluorescence at 665 nm divided by the relative fluorescence at 620 nm, (665/620 ratio), in the presence of varying concentrations of I and a fixed concentration of enzyme and substrate. Nonlinear regression analysis of this data can be performed using GraphPad Prism 3.0 software selecting four parameter logistic equation, that allows for a variable slope. Y=Bottom+(Top-Bottom)/(1+10^((LogEC50−X)*Hill Slope)); X is the logarithm of concentration of I, Y is the percent change in ratio and Y starts at bottom and goes to top with a sigmoid shape.

Human mature Renin enzyme assay

Human Renin can be cloned from a human kidney cDNA library and C-terminally epitope-tagged with the V5-6His sequence into pCDNA3.1. pCNDA3.1-Renin-V5-6His is stably expressed in HEK293 cells and purified to >80% using standard Ni-Affinity chromatography. The prodomain of the recombinant human renin-V5-6His can be removed by limited proteolysis using immobilized TPCK-trypsin to give mature-human renin. Renin enzymatic activity can be monitored using a commercially available fluorescence resonance energy transfer (FRET) peptide substrate, RS-1 (Molecular Probes, Eugene, Oreg.) in 50 mM Tris-HCl pH 8.0, 100 mM NaCl, 0.1% Brij-35 and 5% DMSO buffer for 40 mins at 30° celsius in the presence or absence of different concentrations of test compounds. Mature human Renin is present at approximately 200 nM. Inhibitory activity is defined as the percent decrease in renin induced fluorescence at the end of the 40 min incubation compared to vehicle controls and samples lacking enzyme.

In the aspect of the invention relating to a combination of at least one compound of formula I with at least one cholinesterase inhibitor, acetyl- and/or butyrylcholinesterase inhibitors can be used. Examples of cholinesterase inhibitors are tacrine, donepezil, rivastigmine, galantamine, pyridostigmine and neostigmine, with tacrine, donepezil, rivastigmine and galantamine being preferred. Preferably, these combinations are directed to the treatment of Alzheimer's Disease.

In one aspect of the invention, a combination of at least one compound of formula I with at least one muscarinic m₁ agonist or m₂ antagonist can be used. Examples of m_(i) agonists are known in the art. Examples of m₂ antagonists are also known in the art; in particular, m₂ antagonists are disclosed in U.S. Pat. Nos. 5,883,096; 6,037,352; 5,889,006; 6,043,255; 5,952,349; 5,935,958; 6,066,636; 5,977,138; 6,294,554; 6,043,255; and 6,458,812; and in WO 03/031412, all of which are incorporated herein by reference.

In other aspects of the invention relating to a combination of at least one compound of formula I and at least one other agent, for example a beta secretase inhibitor; a gamma secretase inhibitor; an HMG-CoA reductase inhibitor such as atorvastatin, lovastatin, simvastatin, pravastatin, fluvastatin and rosuvastatin; non-steroidal anti-inflammatory agents such as, but not necessarily limited to ibuprofen, relafen or naproxen; N-methyl-D-aspartate receptor antagonists such as memantine; anti-amyloid antibodies including humanized monoclonal antibodies; vitamin E; nicotinic acetylcholine receptor agonists; CB1 receptor inverse agonists or CB1 receptor antagonists; antibiotics such as doxycycline; growth hormone secretagogues; histamine H3 antagonists; AMPA agonists; PDE4 inhibitors; GABA_(A) inverse agonists; inhibitors of amyloid aggregation; glycogen synthase kinase beta inhibitors; promoters of alpha secretase activity. Preferably, these combinations are directed to the treatment of Alzheimer's Disease.

For preparing pharmaceutical compositions from the compounds described by this invention, inert, pharmaceutically acceptable carriers can be either solid or liquid. Solid form preparations include powders, tablets, dispersible granules, capsules, cachets and suppositories. The powders and tablets may be comprised of from about 5 to about 95 percent active ingredient. Suitable solid carriers are known in the art, e.g. magnesium carbonate, magnesium stearate, talc, sugar or lactose. Tablets, powders, cachets and capsules can be used as solid dosage forms suitable for oral administration. Examples of pharmaceutically acceptable carriers and methods of manufacture for various compositions may be found in A. Gennaro (ed.), Remington's Pharmaceutical Sciences, 18th Edition, (1990), Mack Publishing Co., Easton, Pa.

Liquid form preparations include solutions, suspensions and emulsions. As an example may be mentioned water or water-propylene glycol solutions for parenteral injection or addition of sweeteners and opacifiers for oral solutions, suspensions and emulsions. Liquid form preparations may also include solutions for intranasal administration.

Aerosol preparations suitable for inhalation may include solutions and solids in powder form, which may be in combination with a pharmaceutically acceptable carrier, such as an inert compressed gas, e.g. nitrogen.

Also included are solid form preparations which are intended to be converted, shortly before use, to liquid form preparations for either oral or parenteral administration. Such liquid forms include solutions, suspensions and emulsions.

The compounds of the invention may also be deliverable transdermally. The transdermal compositions can take the form of creams, lotions, aerosols and/or emulsions and can be included in a transdermal patch of the matrix or reservoir type as are conventional in the art for this purpose.

Preferably the compound is administered orally. Preferably, the pharmaceutical preparation is in a unit dosage form. In such form, the preparation is subdivided into suitably sized unit doses containing appropriate quantities of the active component, e.g., an effective amount to achieve the desired purpose.

The quantity of active compound in a unit dose of preparation may be varied or adjusted from about 1 mg to about 100 mg, preferably from about 1 mg to about 50 mg, more preferably from about 1 mg to about 25 mg, according to the particular application.

The actual dosage employed may be varied depending upon the requirements of the patient and the severity of the condition being treated. Determination of the proper dosage regimen for a particular situation is within the skill of the art. For convenience, the total daily dosage may be divided and administered in portions during the day as required.

The amount and frequency of administration of the compounds of the invention and/or the pharmaceutically acceptable salts thereof will be regulated according to the judgment of the attending clinician considering such factors as age, condition and size of the patient as well as severity of the symptoms being treated. A typical recommended daily dosage regimen for oral administration can range from about 1 mg/day to about 300 mg/day, preferably 1 mg/day to 50 mg/day, in two to four divided doses.

When a compound of formula I is used in combination with a cholinesterase inhibitor to treat cognitive disorders, these two active components may be co-administered simultaneously or sequentially, or a single pharmaceutical composition comprising a compound of formula I and a cholinesterase inhibitor in a pharmaceutically acceptable carrier can be administered. The components of the combination can be administered individually or together in any conventional oral or parenteral dosage form such as capsule, tablet, powder, cachet, suspension, solution, suppository, nasal spray, etc. The dosage of the cholinesterase inhibitor can be determined from published material, and may range from 0.001 to 100 mg/kg body weight.

When separate pharmaceutical compositions of a compound of formula I and a cholinesterase inhibitor are to be administered, they can be provided in a kit comprising in a single package, one container comprising a compound of formula I in a pharmaceutically acceptable carrier, and a separate container comprising a cholinesterase inhibitor in a pharmaceutically acceptable carrier, with the compound of formula I and the cholinesterase inhibitor being present in amounts such that the combination is therapeutically effective. A kit is advantageous for administering a combination when, for example, the components must be administered at different time intervals or when they are in different dosage forms.

While the present invention has been described in conjunction with the specific embodiments set forth above, many alternatives, modifications and variations thereof will be apparent to those of ordinary skill in the art. All such alternatives, modifications and variations are intended to fall within the spirit and scope of the present invention. 

1. A compound having the structural formula

or a stereoisomer or tautomer thereof, or a pharmaceutically acceptable salt of said compound, stereoisomer, or tautomer, wherein R¹, R² and R⁵ are independently selected from the group consisting of H, alkyl, arylalkyl, heteroarylalkyl, cycloalkylalkyl, heterocycloalkylalkyl, arylcycloalkylalkyl, heteroarylcycloalkylalkyl, arylheterocycloalkylalkyl, heteroarylheterocycloalkylalkyl, cycloalkyl, arylcycloalkyl, heteroarylcycloalkyl, heterocycloalkyl, arylheterocycloalkyl, heteroarylheterocycloalkyl, alkenyl, arylalkenyl, cycloalkenyl, arylcycloalkenyl, heteroarylcycloalkenyl, heterocycloalkenyl, arylheterocycloalkenyl, heteroarylheterocycloalkenyl, alkynyl, arylalkynyl, aryl, cycloalkylaryl, heterocycloalkylaryl, heterocycloalkenylaryl, heteroaryl, cycloalkylheteroaryl, heterocycloalkylheteroaryl, cycloalkenylaryl, heterocycloalkenylaryl, —OR¹⁵, —CN, —C(O)R⁸, —C(O)OR⁹, —S(O)R¹⁰, —S(O)₂R¹⁰, —C(O)N(R¹¹)(R¹²), —S(O)N(R¹¹)(R¹²), —S(O)₂N(R¹¹)(R¹²), —NO₂, —N═C(R⁸)₂ and —N(R⁸)₂; R³ and R⁴ are independently selected from the group consisting of H, alkyl, arylalkyl, heteroarylalkyl, cycloalkylalkyl, heterocycloalkylalkyl, arylcycloalkylalkyl, heteroarylcycloalkylalkyl, arylheterocycloalkylalkyl, heteroarylheterocycloalkylalkyl, cycloalkyl, arylcycloalkyl, heteroarylcycloalkyl, heterocycloalkyl, arylheterocycloalkyl, heteroarylheterocycloalkyl, alkenyl, arylalkenyl, cycloalkenyl, arylcycloalkenyl, heteroarylcycloalkenyl, heterocycloalkenyl, arylheterocycloalkenyl, heteroarylheterocycloalkenyl, alkynyl, arylalkynyl, aryl, cycloalkylaryl, heterocycloalkylaryl, heterocycloalkenylaryl, heteroaryl, cycloalkylheteroaryl, heterocycloalkylheteroaryl, cycloalkenylaryl, heterocycloalkenylaryl, —CH₂—O—Si(R⁹)(R¹⁰)(R¹⁹), —CN, —C(O)R⁸, —C(O)OR⁹ or —C(O)N(R¹¹)(R¹²); or optionally, R³ and R⁴ together with the carbon atom to which they are attached form a 3- to 8-membered cycloalkyl ring optionally substituted by 1 to 4 R¹⁴ moieties; wherein 1-5 of the atoms in the ring can be replaced by —O—; —S—; —N(R⁵)—; —C(O)—; —S(O)— or —S(O)₂—; R⁸ is independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, —OR¹⁵, —N(R¹⁵)(R¹⁶), —N(R¹⁵)C(O)R¹⁶, —N(R¹⁵)S(O)R¹⁶, —N(R¹⁵)S(O)₂R¹⁶, —N(R¹⁵)S(O)₂N(R¹⁶)(R¹⁷), —N(R¹⁵)S(O)N(R¹⁶)(R¹⁷), —N(R¹⁵)C(O)N(R¹⁶)(R¹⁷) and —N(R¹⁵)C(O)OR¹⁶; R⁹ is independently selected from the group consisting of H, alkyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl and heteroarylalkyl; R¹⁰ is independently selected from the group consisting of H, alkyl, alkenyl, cycloalkyl, cycloalkylalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl and —N(R¹⁵)(R¹⁶); R¹¹ and R¹² are independently selected from the group consisting of H, alkyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, —C(O)R⁸, —C(O)OR⁹, —S(O)R¹⁰, —S(O)₂R¹⁰, —C(O)N(R¹⁵)(R¹⁶), —S(O)N(R¹⁵)(R¹⁶) and —S(O)₂N(R¹⁵)(R¹⁶); each R¹⁴ is independently selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, halo, —CN, —OR¹⁵, —C(O)R¹⁵, —C(O)OR¹⁵, —C(O)N(R¹⁵)(R¹⁶), —SR¹⁵, —S(O)N(R¹⁵)(R¹⁶), —S(O)₂N(R¹⁵)(R¹⁶), —C(═NOR¹⁵)R¹⁶, —P(O)(OR¹⁵)(OR¹⁶), —N(R¹⁵)(R¹⁶), —N(R¹⁵)C(O)R¹⁶, —N(R¹⁵)S(O)R¹⁶, —N(R¹⁵)S(O)₂R¹⁶, —N(R¹⁵)S(O)₂N(R¹⁶)(R¹⁷), —N(R¹⁵)S(O)N(R¹⁶)(R¹⁷), —N(R¹⁵)C(O)N(R¹⁶)(R¹⁷) and —N(R¹⁵)C(O)OR¹⁶; R¹⁵, R¹⁶ and R¹⁷ are independently selected from the group consisting of H, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, arylcycloalkyl, arylheterocycloalkyl, R¹⁸-alkyl, R¹⁸-cycloalkyl, R¹⁸-cycloalkylalkyl, R¹⁸-heterocycloalkyl, R¹⁸-heterocycloallkylalkyl, R¹⁸-aryl, R¹⁸-arylalkyl, R¹⁸-heteroaryl and R¹⁸-heteroarylalkyl; or R¹⁵, R¹⁶ and R¹⁷ are

wherein R²³ numbers 0 to 5 substituents, m is 0 to 6 and n is 1 to 5; R¹⁸ is 1-5 substituents independently selected from the group consisting of alkyl, alkenyl, aryl, arylalkyl, arylalkenyl, arylalkynyl, —NO₂, halo, heteroaryl, HO-alkyoxyalkyl, —CF₃, —CN, alkyl-CN, —C(O)R¹⁹, —C(O)OH, —C(O)OR¹⁹, —C(O)NHR²⁰, —C(O)NH₂, —C(O)N(alkyl)₂, —C(O)N(alkyl)(aryl), —C(O)N(alkyl)(heteroaryl), —SR¹⁹, —S(O)₂R²⁰, —S(O)NH₂, —S(O)NH(alkyl), —S(O)N(alkyl)(alkyl), —S(O)NH(aryl), —S(O)₂NH₂, —S(O)₂NHR¹⁹, —S(O)₂NH(heterocycloalkyl), —S(O)₂N(alkyl)₂, —S(O)₂N(alkyl)(aryl), —OCF₃, —OH, —OR²⁰, —O-heterocycloalkyl, —O-cycloalkylalkyl, —O-heterocycloalkylalkyl, —NH₂, —NHR²⁰, —N(alkyl)₂, —N(arylalkyl)₂, —N(arylalkyl)-(heteroarylalkyl), —NHC(O)R²⁰, —NHC(O)NH₂, —NHC(O)NH(alkyl), —NHC(O)N(alkyl)(alkyl), —N(alkyl)C(O)NH(alkyl), —N(alkyl)C(O)N(alkyl)(alkyl), —NHS(O)₂R²⁰, —NHS(O)₂NH(alkyl), —NHS(O)₂N(alkyl)(alkyl), —N(alkyl)S(O)₂NH(alkyl) and —N(alkyl)S(O)₂N(alkyl)(alkyl); or two R¹⁸ moieties on adjacent carbons can be linked together to form

R¹⁹ is alkyl, cycloalkyl, aryl, arylalkyl or heteroarylalkyl; R²⁰ is alkyl, cycloalkyl, aryl, halo substituted aryl, arylalkyl, heteroaryl or heteroarylalkyl; and wherein each of the alkyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, alkenyl and alkynyl groups in R¹, R², R³, R⁴, R⁵, R⁸, R⁹, R¹⁰, R¹¹, R¹², and R¹⁴ are independently unsubstituted or substituted by 1 to 5 R²¹ groups independently selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, halo, —CN, —OR¹⁵, —C(O)R¹⁵, —C(O)OR¹⁵, —C(O)N(R¹⁵)(R¹⁶), —SR¹⁵, —S(O)N(R¹⁵)(R¹⁶), —CH(R ₁₅)(R¹⁶), —S(O)₂N(R¹⁵)(R¹⁶), —C(═NOR¹⁵)R¹⁶, —P(O)(OR¹⁵)(OR¹⁶), —N(R¹⁵)(R¹⁶), -alkyl-N(R¹⁵)(R¹⁶), —N(R¹⁵)C(O)R¹⁶, —CH₂—N(R¹⁵)C(O)R¹⁶, —CH₂—R¹⁵; —N(R¹⁵)S(O)R¹⁶, —N(R¹⁵)S(O)₂R¹⁶, —CH₂—N(R¹⁵)S(O)₂R¹⁶, —N(R¹⁵)S(O)₂N(R¹⁶)(R¹⁷), —N(R¹⁵)S(O)N(R¹⁶)(R¹⁷), —N(R¹⁵)C(O)N(R¹⁶)(R¹⁷), —CH₂—N(R¹⁵)C(O)N(R¹⁶)(R¹⁷), —N(R¹⁵)C(O)OR¹⁶, —CH₂—N(R¹⁵)C(O)OR¹⁶, —S(O)R¹⁵, ═NOR¹⁵, —N₃, —NO₂ and —S(O)₂R¹⁵; and wherein each of the alkyl, cycloalkenyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, alkenyl and alkynyl groups in R²¹ are independently unsubstituted or substituted by 1 to 5 R²² groups independently selected from the group consisting of alkyl, cycloalkyl, cycloalkenyl, heterocycloalkyl, aryl, heteroaryl, halo, —CF₃, —CN, —OR¹⁵, —C(O)R¹⁵, —C(O)OR¹⁵, -alkyl-C(O)OR¹⁵, C(O)N(R¹⁵)(R¹⁶), —SR¹⁵, —S(O)N(R¹⁵)(R¹⁶), —S(O)₂N(R¹⁵)(R¹⁶), —C(═NOR¹⁵)R¹⁶, —P(O)(OR¹⁵)(OR¹⁶), —N(R¹⁵)(R¹⁶), -alkyl-N(R¹⁵)(R¹⁶), —N(R¹⁵)C(O)R¹⁶, —CH₂—N(R¹⁵)C(O)R¹⁶, —N(R¹⁵)S(O)R¹⁶, —N(R¹⁵)S(O)₂R¹⁶, —CH₂—N(R¹⁵)S(O)₂R¹⁶, —N(R¹⁵)S(O)₂N(R¹⁶)(R¹⁷), —N(R¹⁵)S(O)N(R¹⁶)(R¹⁷), —N(R¹⁵)C(O)N(R¹⁶)(R¹⁷), —CH₂—N(R¹⁵)C(O)N(R¹⁶)(R¹⁷), —N(R¹⁵)C(O)OR¹⁶, —CH₂—N(R¹⁵)C(O)OR¹⁶, —N₃, ═NOR¹⁵, —NO₂, —S(O)R¹⁵ and —S(O)₂R¹⁵; or two R²¹ or two R²² moieties on adjacent carbons can be linked together to form

and when R²¹ or R²² are selected from the group consisting of —C(═NOR¹⁵)R¹⁶, —N(R¹⁵)C(O)R¹⁶, —CH₂—N(R¹⁵)C(O)R¹⁶, —N(R¹⁵)S(O)R¹⁶, —N(R¹⁵)S(O)₂R¹⁶, —CH₂—N(R¹⁵)S(O)₂R¹⁶, —N(R¹⁵)S(O)₂N(R¹⁶)(R¹⁷), —N(R¹⁵)S(O)N(R¹⁶)(R¹⁷), —N(R¹⁵)C(O)N(R¹⁶)(R¹⁷), —CH₂—N(R¹⁵)C(O)N(R¹⁶)(R¹⁷), —N(R¹⁵)C(O)OR¹⁶ and —CH₂—N(R¹⁵)C(O)OR¹⁶, R¹⁵ and R¹⁶ together can be a C₂ to C₄ chain wherein, optionally, one, two or three ring carbons can be replaced by —C(O)— or —N(H)— and R¹⁵ and R¹⁶, together with the atoms to which they are attached, form a 5 to 7 membered ring, optionally substituted by R²³; R²³ is 1 to 5 groups independently selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, cycloalkenyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, halo, —CN, —OR²⁴, —C(O)R²⁴, —C(O)OR²⁴, —C(O)N(R²⁴)(R²⁵), —SR²⁴, —S(O)N(R²⁴)(R²⁵), —S(O)₂N(R²⁴)(R²⁵), —C(═NOR²⁴)R²⁵, —P(O)(OR²⁴)(OR²⁵), —N(R²⁴)(R²⁵), -alkyl-N(R²⁴)(R²⁵), —N(R²⁴)C(O)R²⁵, —CH₂—N(R²⁴)C(O)R²⁵, —N(R²⁴)S(O)R²⁵, —N(R²⁴)S(O)₂R²⁵, —CH₂—N(R²⁴)S(O)₂R²⁵, —N(R²⁴)S(O)₂N(R²⁵)(R²⁶), —N(R²⁴)S(O)N(R²⁵)(R²⁶), —N(R²⁴)C(O)N(R²⁵)(R²⁶), —CH₂—N(R²⁴)C(O)N(R²⁵)(R²⁶), —N(R²⁴)C(O)OR²⁵, —CH₂—N(R²⁴)C(O)OR²⁵, —S(O)R²⁴ and —S(O)₂R²⁴; and wherein each of the alkyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, alkenyl and alkynyl groups in R²³ are independently unsubstituted or substituted by 1 to 5 R²⁷ groups independently selected from the group consisting of alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, halo, —CF₃, —CN, —OR²⁴, —C(O)R²⁴, —C(O)OR²⁴, -alkyl-C(O)OR²⁴, —C(O)N(R²⁴)(R²⁵), —SR²⁴, —S(O)N(R²⁴)(R²⁵), —S(O)₂N(R²⁴)(R²⁵), —C(═NOR²⁴)R²⁵, —P(O)(OR²⁴)(OR²⁵), —N(R²⁴)(R²⁵), -alkyl-N(R²⁴)(R²⁵), —N(R²⁴)C(O)R²⁵, —CH₂—N(R²⁴)C(O)R²⁵, —N(R²⁴)S(O)R²⁵, —N(R²⁴)S(O)₂R²⁵, —CH₂—N(R²⁴)S(O)₂R²⁵, —N(R²⁴)S(O)₂N(R²⁵)(R²⁶), —N(R²⁴)S(O)N(R²⁵)(R²⁶), —N(R²⁴)C(O)N(R²⁵)(R²⁶), —CH₂—N(R²⁴)C(O)N(R²⁵)(R²⁶), —N(R²⁴)C(O)OR²⁵, —CH₂—N(R²⁴)C(O)OR²⁵, —S(O)R²⁴ and —S(O)₂R²⁴; R²⁴, R²⁵ and R²⁶ are independently selected from the group consisting of H, alkyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, heterocycloalkylalkyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, arylcycloalkyl, R²⁷-alkyl, R²⁷-cycloalkyl, R²⁷-cycloalkylalkyl, R²⁷-heterocycloalkyl, R²⁷-heterocycloalkylalkyl, R²⁷-aryl, R²⁷-arylalkyl, R²⁷-heteroaryl and R²⁷-heteroarylalkyl; R²⁷ is 1-5 substituents independently selected from the group consisting of alkyl, aryl, arylalkyl, —NO₂, halo, —CF₃, —CN, alkyl-CN, —C(O)R²⁸, —C(O)OH, —C(O)OR²⁸, —C(O)NHR²⁹, —C(O)N(alkyl)₂, —C(O)N(alkyl)(aryl), —C(O)N(alkyl)(heteroaryl), —SR²⁸, —S(O)₂R²⁹, —S(O)NH₂, —S(O)NH(alkyl), —S(O)N(alkyl)(alkyl), —S(O)NH(aryl), —S(O)₂NH₂, —S(O)₂NHR²⁸, —S(O)₂NH(aryl), —S(O)₂NH(heterocycloalkyl), —S(O)₂N(alkyl)₂, —S(O)₂N(alkyl)(aryl), —OH, —OR²⁹, —O-heterocycloalkyl, —O-cycloalkylalkyl, —O-heterocycloalkylalkyl, —NH₂, —NHR²⁹, —N(alkyl)₂, —N(arylalkyl)₂, —N(arylalkyl)(heteroarylalkyl), —NHC(O)R²⁹, —NHC(O)NH₂, —NHC(O)NH(alkyl), —NHC(O)N(alkyl)(alkyl), —N(alkyl)C(O)NH(alkyl), —N(alkyl)C(O)N(alkyl)(alkyl), —NHS(O)₂R²⁹, —NHS(O)₂NH(alkyl), —NHS(O)₂N(alkyl)(alkyl), —N(alkyl)S(O)₂NH(alkyl) and —N(alkyl)S(O)₂N(alkyl)(alkyl); R²⁸ is alkyl, cycloalkyl, arylalkyl or heteroarylalkyl; and R²⁹ is alkyl, cycloalkyl, aryl, arylalkyl, heteroaryl or heteroarylalkyl.
 2. A compound of claim 1, or a stereoisomer or tautomer thereof, or a pharmaceutically acceptable salt of said compound, stereoisomer, or tautomer, said compound having the following structure:


3. A compound of claim 1 wherein R¹ is alkyl, heterocycloalkyl or heterocycloalkylalkyl.
 4. A compound of claim 1 wherein R² is H or alkyl.
 5. A compound of claim 1 wherein R³ is aryl, heteroaryl, alkyl, cycloalkyl or cycloalkylalkyl.
 6. A compound of claim 1 wherein R⁴ is alkyl.
 7. A compound of claim 1 wherein R⁵ is hydrogen.
 8. A compound of claim 1 having the formula:

wherein R¹⁴ is aryl, heteroaryl, alkyl, cycloalkyl or cycloalkylalkyl.
 9. A compound of claim 1 wherein R³ is aryl-substituted aryl, heteroaryl-substituted aryl, aryl-substituted heteroaryl or heteroaryl-substituted heteroaryl, aryl-substituted cycloalkyl, heteroaryl-substituted cycloalkyl, aryl-substituted alkyl, heteroaryl-substituted alkyl, aryl-substituted cycloalkyl or heteroaryl-substituted cycloalkylalkyl.
 10. A compound of claim 1 wherein R³ is


11. A compound of claim 1 wherein R¹ is alkyl, heterocycloalkyl or heterocycloalkylalkyl; R² is H or alkyl; R³ is aryl, heteroaryl, alkyl, cycloalkyl or cycloalkylalkyl; R⁴ is alkyl; and R⁵ is hydrogen.
 12. A compound of claim 11 having the formula:

wherein R¹⁴ is aryl, heteroaryl, alkyl, cycloalkyl or cycloalkylalkyl.
 13. A compound of claim 8 wherein R³ is aryl-substituted aryl, heteroaryl-substituted aryl, aryl-substituted heteroaryl or heteroaryl-substituted heteroaryl, aryl-substituted cycloalkyl, heteroaryl-substituted cycloalkyl, aryl-substituted alkyl, heteroaryl-substituted alkyl, aryl-substituted cycloalkyl or heteroaryl-substituted cycloalkylalkyl.
 14. A compound of claim 8 wherein R³ is selected from the group consisting of


15. A pharmaceutical composition comprising an effective amount of a compound of claim 1 and a pharmaceutically acceptable carrier. 